The present invention relates to complex compounds containing acesulfame which have an antimicrobial action, in particular an antibacterial action.
Various metal cations, for example zinc(II), copper(II) and silver(I) ions, and also quaternary ammonium cations, for example the cetylpyridinium cation, have antimicrobial action and are therefore used to eliminate or reduce unwanted microorganisms, for example bacteria and viruses, in foods and feeds. Antimicrobially active cations are also frequently used in oral care compositions and pharmaceuticals against bacteria and viruses which lead to infections, for example stomatitis, laryngitis, herpes or caries, in the oral and pharyngeal cavities.
Zinc(II) ions are described in WO 97/40812 and WO 00/00166 as active compounds against halitosis, dental plaque, dental tartar and infections in the oral area. It is known that zinc(II) salts inhibit proteolysis by direct action on the proteases of the bacteria. These are cysteine and methionine proteases which can cause halitosis by release of sulfur compounds (Marsh, P D, J. Clin. Peridontal 18 (6) 462-467,1991). WO 00/62738 describes a lipstick to combat halitosis which comprises zinc(II) citrate as antibacterial active compound.
Zinc(II) ions are known to show their antibacterial activity in particular against those bacteria which cause caries, for example Streptococcus mutans (see Watson, G. K.; Cummins, D.; Van der Ouderaa, F. J. G. Caries Res. (1991), 25(6), 431-7). Colgate PerioGard(copyright) Pluse toothpaste contains, for example, zinc(II) citrate as active compound against caries.
The antiviral activity of zinc(II) ions against Herpes simplex and rhinoviruses has been described in many publications and patents (for example Arens, Max; Travis, Sharon, J. Clin. Microbiol. (2000), 38(5), 1758-1762; WO 99/55342).
Copper(II) ions, owing to their antibacterial action, in particular in oral hygiene, are used in the form of citrates, bisglycinates or bicarbonates (see U.S. Pat. Nos. 4,332,791, 4,652,444, 5,037,634 and 5,389,360).
Silver(I) ions are occasionally used for preparing and sterilizing drinking water in small amounts which are sufficient to obtain permanent sterilization and long-term maintenance of freshness of the water owing to the bactericidal action of the silver compounds (see WO 96/01231, U.S. Pat. No. 5,366,636).
K. Yamamoto et al. (Dent. Mater. (1996), 12(4), 227-229) report the antibacterial activity of silver(I) ions which are implanted in silicate fillings against streptococci occurring in the mouth.
Silver(I) ions are also used in mouthwashes for withdrawal from the smoking habit (see U.S. Pat. No. 5,032,612). During smoking, in the presence of silver(I) ions nicotine forms nicotinamide which causes an unpleasant taste in the mouth, so that an aversion to cigarette smoke is said to be formed (U.S. Pat. No. 5,122,366). Silver(I) acetate, incorporated into tablets for sucking, is also said to be suitable for successful therapies for withdrawal from smoking (see U.S. Pat. No. 4,832,994).
Cetylpyridinium cations have, as quaternary ammonium compounds, an antibacterial action and are used in particular in mouthwashes (see WO 00/51559, WO 00/44338). EP-A-0 399 479 and GB-A 2348370 describe a chewing gum for oral and pharyngeal disinfection in which cetylpyridinium cations form the antibacterially active constituent. WO 97/38586 reports a method which is said to achieve inhibition or elimination of bacteria in contaminated foods by means of quaternary ammonium compounds. This method uses quaternary ammonium compounds, in particular cetylpyridinium chloride, which, in foods, eliminates microorganisms, for example staphylococci, listeria, salmonellae, Escherichia coli bacteria and fungi such as Aspergillus flavus. The quaternary ammonium compounds are applied in dissolved form by spraying onto foods such as meat, fish, vegetables and fruit.
Furthermore, cetylpyridinium cations are used in numerous pharmaceutical preparations, for example in (copyright)Hextrilettes from Warner Lambert, (copyright)Dobendan from Boots Healthcare and (copyright)Frubienzym from Boehringer Ingelheim Pharma KG as tablets for sucking in the case of infections of the oral, neck and throat cavity which are caused by viruses and bacteria. Cetylpyridinium chloride accumulates on the cell walls of the pathogens, destroys them and kills the germs.
Colgate PerioGard Plus(copyright) oral rinse also comprises cetylpyridinium chloride in active amounts.
Synergistic combinations of zinc(II) salts and cetylpyridinium chloride against halitosis are also described in WO 00/51559.
The focus of the present invention is in the field of use of antibacterial cations, in particular in the oral hygiene sector. The widespread disease caries which is caused by bacteria, for example Streptococcus mutans, can be restricted by antibacterially active cations. Halitosis is caused in many cases by bacteria which decompose food residues present in the mouth and release sulfur compounds. Elderly people and diabetes patients frequently complain of xerostomia, which is caused by a decreased production of saliva in the mouth. Xerostomia is an ideal growth medium for bacteria, so that infections, halitosis and caries are observed significantly precisely in the case of diabetes. Food residues and bacteria can no longer be washed away in xerostomia due to the lack of saliva. The consequence is that the bacteria in the mouth can multiply better on the rich supply of nutrient media. In order that pathogens and their consequences, for example caries or halitosis, can be reduced or eliminated, antimicrobially active cations are used in toothpaste, chewing gums and mouthwashes.
However, it is a problem that many salts of the above-described antimicrobially active cations, even in small amounts, taste unpleasant, and in particular, have an astringent taste. The incorporation of compounds of these antibacterially active cations into foods, dental care compositions, drugs or feeds and supplying them via special preparations is therefore a difficult undertaking on account of the lack of acceptance by humans and animals.
An object of the present invention was thus to provide a form which tastes as pleasant as possible of antimicrobial, in particular antibacterial, active compounds with which the acceptance and possibilities of targeted employment of the active compounds in foods, dental care compositions, drugs and feeds can be significantly improved.
Surprisingly, it has been found that the known sweetener acesulfame (6-methyl-3,4-dihydro-1,2,3-oxathiazin-4-one 2,2-dioxide), which has previously only been offered as potassium salt (acesulfame-K), but of which, salts with alkali metals and alkaline earth metals, for example sodium, potassium, magnesium and calcium salts, the acidic acesulfame itself, which is called acesulfamic acid, and some amine salts are also known, forms stable complexes with these antimicrobially active, in particular antibacterially active, cations containing the acesulfame anion. These complexes are distinguished surprisingly by a pleasantly sweet taste which is not associated with the astringent note of many salts of the antibacterially active cations.
The present invention thus achieves the object via complex compounds of metallic elements such as zinc, copper, silver, or nonmetallic quaternary ammonium cations, for example the cetylpyridinium cation, with acesulfame.